1. Field of the Invention.
The present invention relates to a motorcycle spark arrestor and, more particularly, to a self-cleaning, long-lasting, low back pressure spark arrestor for use with motorcycles and the like.
2. Description of the Prior Art.
Federal Law requires all motorcycles used in National Parks to have a spark arrestor. The spark arrestor must have the capability of removing 80% of all carbon particles greater than 0.023 inches. Since the carbon particles accumulate within the arrestor, it must also be periodically cleaned.
As a result of the above requirements, two types of spark arrestors have been developed for use on motorcycles. The first is the purely mechanical type having a series of baffles and other elements to prevent the hot carbon particles from escaping. However, such types present too much of a restriction to the exhaust gases to permit their use with many high performance motorocycles and, as a result, mechanical types are not widely used.
The screen type consists of a stainless steel screen through which the exhaust gases pass. While th simplest screen type could include a planar, cylindrical screen positioned normal to the longitudinal axis of the exhaust pipe, such a screen is not possible since Federal regulations require the open area of the screen to be at least twice the area of the exhaust port of the motorcycle engine. Therefore, in order to provide a sufficient area, the most common type of screen type spark arrestor includes a cone inserted in the tail pipe with the pointed end of the cone facing forward. However, while this type of spark arrestor meets federal requirements, the sharp edge in the path of the hot exhaust gases eventually burns up and steps must be taken to prevent this from happening, increasing the complexity and cost of the spark arrestor.